One example of a prior art HVAC duct system 100 is shown in FIG. 1. In this system, a unit 110, such as a heating or an air conditioning unit, supplies heated or cooled air through a duct system 120 which terminates in a plurality of boots 121-126. In the system 100, dampers 131-136 are provided where feeder lines connect the boots 121-126 to a main line 140 of the duct system 100.
One example of a prior art damper 200 suitably used as each of the dampers 131-136 in FIG. 1 is shown in FIG. 2. A threaded extension 202 is rotatably mounted in a mounting hole and a handle 204 can be employed to open, close or otherwise adjust the position of the damper 200. Wing nut 205 allows the position of damper plate 206 to be locked in place once correctly set with the handle 204.
A problem with approaches like those illustrated in FIGS. 1 and 2 is that they require access to a basement or attic where the duct system is located to adjust air flow by adjusting the dampers, and most homeowners and building owners are not particularly comfortable with crawling around a crawl space or an attic. As an example, a misstep in an unfinished attic can result in stepping through a ceiling resulting in the need for a costly repair.
An alternative prior art approach to the damping arrangement of FIG. 1 is shown in FIGS. 3A-3C (collectively FIG. 3). In the approach illustrated by FIG. 3, a boot 300 having a collar 310 terminates in a ceiling register 320. In the collar, a damper like the damper 200 shown in FIG. 2 is mounted in the collar 310, at the mounting holes 311 and 312. This damper has both the same threaded extension 202, handle 204 and wing nut 205 extending outside the collar 310 as seen in FIG. 3B. The handle 204 is accessed by attic access or by removing the ceiling register 320.